Thought I would resurrect this thread and make amends for my earlier unhelpful remark by making a suggestion. I haven't researched this at all as it pertains to the East, but in the West, most of the hymnography used to be the work of monastics, and it was customary for monastics not to sign their work. That's why so much chant is by "anonymous." Not that it fell out of the sky, or was left on a church doorstep, but the monk (or nun, in some cases) who wrote it didn't want any credit. Maybe that's the case in Orthodoxy, too, although I really don't know.